[Homeroast] Poisson's ratio WAS: Re: Compak vs Macap vs Rocky Grinders

Joseph Robertson theotherjo at gmail.com
Tue May 18 09:59:46 CDT 2010


Mike,
Nice to hear a human description of a "Natural" force of nature.  We being
part of nature. Although some would argue I'm not at all natural of this
earth like my mother who used to ( tongue in cheek I'm sure ) tell friends
when introducing me as a child that "Joe did not come by stork, there was
this small shiny ship that landed one night in our neighborhood." Could this
be why I love Sci fi and this black gold that runs through this list's
vein's? I did a wiki pedia and some other reading so I would have a clue
when you and RayO or anyone else shares information on this 'spro tamping
topic.
Very interesting and fun now back to my coffee.
JoeR

On Tue, May 18, 2010 at 7:34 AM, Mike Koenig <koenig.mike at gmail.com> wrote:

> I'm probably splitting hairs here, but Poisson's effect happens on the
> molecular level, with bonds elongating under pressure or strain.  I'm not a
> geoscience guy, but I imagine the effect effect would happen in rocks,
> dense
> clays and shale, etc,  but what you are seeing in a coffee puck is
> interactions between discrete non-uniform particles.
>
> I'm not arguing at all that you don't get some lateral expansion during
> tamping, since that certainly does happen, but it's not necessarily
> uniform,
> and dependent on the distribution (and re-arrangement under force) of the
> particles, as opposed to poisson's effect, which describes a predictable
> amount of lateral expansion based on the change axial length.  If the
> expansion was due to poisson's effect, the puck would spring back when you
> let go of the tamper.   What you are getting is some re-arrangement of the
> particles under force (like when you step in sand, and it moves out of the
> way under your foot).
>
> --mike
>
>
>
> On Tue, May 18, 2010 at 3:01 AM, <raymanowen at gmail.com> wrote:
>
> > Then I don't know why the grounds would press out and seal against the
> > sides
> > of the basket when you are only applying axial force with the tamper.
> > Hydrostatic?
> >
> > I hope I don't owe a refund of all our pay at the Geophysics Research
> > Institute at CSM. Please don't tell Dr. Levent Ozdemir or Dr. Russ Miller
> > we
> > were doing bad oil shale research. Damn!
> >
> > What supports you when you walk on a sandy beach?
> >
> > Teach me, please. -ro
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